Initial Commit

2026-10-02 21:34:56 +08:00
parent 5a3867ff25
commit 79bf4cdbf2
915 changed files with 20552 additions and 2 deletions
@@ -0,0 +1,168 @@
+"""LVGL v9 RLE codec (LV_IMAGE_COMPRESS_RLE).
+
+Control byte grammar (upstream `lv_rle_decompress`):
+  high bit CLEAR (0x00..0x7F) : repeat the next single `blk`-byte block `ctrl` times
+  high bit SET   (0x80|count) : copy `count` blocks verbatim (literal run)
+  count is 1..=127
+For palette formats (I8) the stream decodes to 256*4 palette bytes followed by
+w*h palette indices.
+"""
+import struct
+from PIL import Image
+
+MAGIC = 0x19
+FLAG_COMPRESSED = 0x08
+METHOD_NONE, METHOD_RLE, METHOD_LZ4 = 0, 1, 2
+
+
+def rle_decompress(data, blk, out_len=None):
+    out = bytearray()
+    i, n = 0, len(data)
+    while i < n:
+        ctrl = data[i]; i += 1
+        if ctrl & 0x80:
+            cnt = ctrl & 0x7F
+            nb = cnt * blk
+            if i + nb > n:
+                raise ValueError('truncated literal run')
+            out += data[i:i + nb]
+            i += nb
+        else:
+            cnt = ctrl
+            if i + blk > n:
+                raise ValueError('truncated repeat unit')
+            unit = data[i:i + blk]
+            i += blk
+            out += unit * cnt
+        if out_len is not None and len(out) >= out_len:
+            break
+    return bytes(out)
+
+
+def rle_compress(raw, max_run=127):
+    """LVGL RLE 编码器（rle_decompress 的逆向，blk=1）。
+
+    贪心：先找同字节游程（>=2 用「重复」指令），否则攒「原样」指令。
+    输出长度总是 <= 原图像素流，因为最坏情况每条 literal 只多 1 个控制字节。
+    """
+    out = bytearray()
+    i, n = 0, len(raw)
+    while i < n:
+        v = raw[i]
+        j = i + 1
+        while j < n and raw[j] == v and j - i < max_run:
+            j += 1
+        run = j - i
+        if run >= 2:
+            out.append(run); out.append(v); i = j
+            continue
+        lit = bytearray()
+        k = i
+        while k < n and len(lit) < max_run:
+            if k + 1 < n and raw[k] == raw[k + 1]:
+                break
+            lit.append(raw[k]); k += 1
+        if not lit:                      # 理论上到不了这里
+            lit.append(v); k = i + 1
+        out.append(0x80 | len(lit)); out += lit
+        i = k
+    return bytes(out)
+
+
+def pad_rle(comp, want):
+    """把 RLE 流补到 want 字节：用 ctrl=0（重复 0 次 = 产出 0 像素）的 2 字节空指令。
+
+    ctrl=0 是合法指令（`len = 0`，两个越界判断都不触发），所以设备端解码器读完 csize
+    字节既不会越界、也不会返回 INVALID —— 这是「等长覆盖」能成立的关键。
+    差值为奇数时先把一条 literal 拆成两条（payload 不变、多 1 个控制字节）。
+    """
+    d = want - len(comp)
+    if d < 0:
+        return None
+    if d % 2:
+        b = bytearray(comp)
+        for idx in range(len(b) - 1, -1, -1):
+            if b[idx] & 0x80 and (b[idx] & 0x7F) >= 2:
+                cnt = b[idx] & 0x7F
+                lit = bytes(b[idx + 1: idx + 1 + cnt])
+                half = cnt // 2
+                b[idx: idx + 1 + cnt] = (bytes([0x80 | half]) + lit[:half] +
+                                         bytes([0x80 | (cnt - half)]) + lit[half:])
+                break
+        else:
+            return None
+        comp = bytes(b)
+        d -= 1
+    return comp + b'\x00\x00' * (d // 2)
+
+
+def parse_header(blob):
+    if len(blob) < 12 or blob[0] != MAGIC:
+        return None
+    magic, cf, flags, w, h, stride, rsv = struct.unpack('<BBHHHHH', blob[:12])
+    return dict(magic=magic, cf=cf, flags=flags, w=w, h=h, stride=stride, reserved=rsv)
+
+
+def decode_lvgl_bin(blob):
+    """Return (header, RGBA PIL image) for uncompressed / RLE LVGL v9 .bin.
+
+    NOTE stride: LVGL pads each row to the header's `stride`, which is NOT always
+    equal to w (e.g. the S5 41mm control-center icons are 116 wide with stride 128).
+    Reading them as w*h contiguous pixels yields rainbow garbage, so the row pitch
+    below is taken from the header.
+    """
+    h = parse_header(blob)
+    if h is None:
+        return None, None
+    cf, w, ht = h['cf'], h['w'], h['h']
+    body = blob[12:]
+    if h['flags'] & FLAG_COMPRESSED:
+        method, csize, usize = struct.unpack('<III', body[:12])
+        if method != METHOD_RLE:
+            raise ValueError(f'unsupported compression method {method}')
+        blk = 4 if cf == 0x10 else 1     # ARGB8888 是 4 字节一块，I8 是 1 字节
+        raw = rle_decompress(body[12:12 + csize], blk, usize)
+    else:
+        raw = body
+    img = Image.new('RGBA', (w, ht))
+    px = img.load()
+    if cf == 0x10:                                  # ARGB8888 (BGRA)
+        pitch = max(h['stride'] or 0, w * 4)
+        if len(raw) < pitch * ht:
+            return h, None
+        for y in range(ht):
+            row = y * pitch
+            for x in range(w):
+                b, g, r, a = raw[row + x * 4:row + x * 4 + 4]
+                px[x, y] = (r, g, b, a)
+    elif cf == 0x0a:                                # I8: palette then indices
+        pitch = max(h['stride'] or 0, w)
+        if len(raw) < 1024 + pitch * ht:
+            return h, None
+        pal = raw[:1024]
+        palette = [(pal[i*4+2], pal[i*4+1], pal[i*4+0], pal[i*4+3]) for i in range(256)]
+        for y in range(ht):
+            row = 1024 + y * pitch
+            for x in range(w):
+                px[x, y] = palette[raw[row + x]]
+    else:
+        return h, None
+    return h, img
+
+
+def pad_rle_safe(comp, want):
+    """把 RLE 流补齐到 want 字节 —— 只用两类**产出 0 像素**的合法指令：
+        ctrl=0x00 + unit  : 重复 0 次（2 字节）
+        0x80              : 原样 0 个（1 字节，用来修奇偶）
+    两者都能通过上游 lv_rle_decompress 的边界判断（len 为 0，不越界）。
+    注意：不要像 pad_rle 那样去“拆一条 literal”修奇偶 —— 那是按裸字节扫描的，
+    会命中负载里的普通字节、把流改坏（本工具就是踩了这个坑才发现）。"""
+    d = want - len(comp)
+    if d < 0:
+        return None
+    out = bytearray(comp)
+    out += b'\x00\x00' * (d // 2)
+    if d % 2:
+        out.append(0x80)
+    assert len(out) == want
+    return bytes(out)